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malammik wrote:
You can't get it to oversteer easily. They made it understeer like that because most people don't know how to drive and don't care to learn. Oversteer causes huge liability for auto makers, and Porsche especially has been burned by this. Its not just the huge rear tires, its the lack of front camber more than anything.
Sort of a pet peeve of mine (I'm igniting a debate here) is this whole inflate/deflate understeer/oversteer thing.
The absolute fact is that there is an IDEAL pressure that will cause a tire to have maximum grip. If you inflate, or deflate beyond that point, you will lose grip.
I don't know whether inflating or deflating causes you to lose grip faster, and I really don't care, neither one is an appropriate way to tune a chassis.
If you inflate your rear tires so that they look like donuts, then your contact patch will be, of course, very narrow, and the rear end will come around faster. This will reduce understeer with the expense of reducing overall grip.
I realize this is Autox lore; it is a typical case of fixing the end that ain't broke. The problems with the 996/997 are that the front tires are too narrow (no you cant fix that with narrower rear tires) and the front camber is not adjustible less than about -1 degrees, if you are lucky!
The best solution, IMHO, is lowering the car which will allow you to have more negative front camber. Heck, our cars sit 1" or so higher than how they were designed for Europe, because of U.S. bumper regulations. I also like to run wider front tires, I have 265's on my 996. I don't know the factory 997 front size, but I'll guess 225. 225 is just not enough. The stage 3 step is to install camber plates. I wouldn't recommend this for a 996/997 because the products available are not quite ready for daily driving.
As an aside, any guesses what size tires they run on Grand-Am 997 Cup Cars????
2-20.9 Tire sizes are 280/640R18 front and 305/680R18 rear
This all said (as Kam always reminds me) you learn more by driving what you have, and driving cars that aren't perfect, than by continually making changes. And obviously an understeering car is more safe than any other condition.
Quote:Today was a blast. My left knee is blistered from rubbing against the door but I will fix myself up before tomorrow with some of the painters tape I ripped off Steve's carhock:
Even on the skid pad, I could not get my car to oversteer. Must be because of those huge rear tires. Understeer no problem. Plenty of that :X.
Should I try to lower the pressure in the front and increase a little in the back? Any specific values that had worked for you in a 997?
C'yall tomorrow.
You can't get it to oversteer easily. They made it understeer like that because most people don't know how to drive and don't care to learn. Oversteer causes huge liability for auto makers, and Porsche especially has been burned by this. Its not just the huge rear tires, its the lack of front camber more than anything.
Sort of a pet peeve of mine (I'm igniting a debate here) is this whole inflate/deflate understeer/oversteer thing.
The absolute fact is that there is an IDEAL pressure that will cause a tire to have maximum grip. If you inflate, or deflate beyond that point, you will lose grip.
I don't know whether inflating or deflating causes you to lose grip faster, and I really don't care, neither one is an appropriate way to tune a chassis.
If you inflate your rear tires so that they look like donuts, then your contact patch will be, of course, very narrow, and the rear end will come around faster. This will reduce understeer with the expense of reducing overall grip.
I realize this is Autox lore; it is a typical case of fixing the end that ain't broke. The problems with the 996/997 are that the front tires are too narrow (no you cant fix that with narrower rear tires) and the front camber is not adjustible less than about -1 degrees, if you are lucky!
The best solution, IMHO, is lowering the car which will allow you to have more negative front camber. Heck, our cars sit 1" or so higher than how they were designed for Europe, because of U.S. bumper regulations. I also like to run wider front tires, I have 265's on my 996. I don't know the factory 997 front size, but I'll guess 225. 225 is just not enough. The stage 3 step is to install camber plates. I wouldn't recommend this for a 996/997 because the products available are not quite ready for daily driving.
As an aside, any guesses what size tires they run on Grand-Am 997 Cup Cars????
2-20.9 Tire sizes are 280/640R18 front and 305/680R18 rear
This all said (as Kam always reminds me) you learn more by driving what you have, and driving cars that aren't perfect, than by continually making changes. And obviously an understeering car is more safe than any other condition.